Medical facilities such as hospitals and medical laboratories have a need to transport and preserve samples, vaccines, medicines and even human organs under cool or cold conditions and frequently under sterile conditions. Further, it is frequently necessary to transport such materials in a vehicle without having access to an electrical outlet.
In the past there have been many well know portable sublimation refrigerator-freezers that have been used for storing and/or transporting medical supplies and food items. For example, a Roncaglione U.S. Pat. No. 4,288,996 discloses a sublimation refrigerator having a thermally insulated outer housing with a pivotal top. A small insulated dry ice chamber is adapted to be supported centrally within the container as is a separate insulated freezer compartment having a removable top. A first set of serpentine cooling coils are supported in the interior side walls of the main insulated container and in the side walls of the freezer compartment. One end of each of these coils connects to the dry ice chamber. A bubble type visual flow indicator having a transparent window is supported on the exterior of the main container. The output ends of both the freezer coil and the cooler coil connect to the visual indicator through manually adjustable flow control valves. The output of the visual indicator vents to the atmosphere. In normal use, the valve at the output of the freezer coil is opened allowing the flow of gas sublimating from the dry ice through the freezer coil so that a very low temperature is attained within the freezer. The valve at the output of the cooler coil is then used to control the flow to attain a desired cooler temperature and the freezer valve may be temporarily closed allowing the visual indicator to be used for adjustment of the cooler coil. Since both freezer and cooler coils are fed simultaneously control of each area is by the valves, and closing either one will allow all gases to go through a desired area.
A more recent Howcroft U.S. Pat. No. 5,709,104 for a cooling device for an insulated ice chest discloses a portable cooling apparatus. The apparatus includes a thermally insulated housing, such as a conventional hand carried ice chest with a lid for removably covering the main opening. A thermally insulated dry ice chamber is disposed inside the chest. The dry ice chamber is vented and a fan is contained within the chamber. Dry ice is placed in the chamber and sublimates into cold gas which expands and passes from the vented chamber into the chest to cool the chest. Cooling action is increased by selectively actuating the fan to drive the sublimated gas rapidly into the chest, thereby causing air movement within the chest in a circulating flow pattern passing through the ice chamber.
Finally, a Costanzo U.S. Pat. No. 7,481,070 discloses a solar powered chilled cooler. As disclosed therein the cooler includes a plurality of coolant lines embedded in a plurality of walls of the cooler unit. The coolant lines include coolant fluid; a compressor coupled to the coolant lines; a fan adapted to circulate air around the coolant lines; a thermostat adapted to measure the cooler unit internal temperature; a temperature adjust control coupled to the compressor and to the thermostat; the temperature adjust control adapted to cause the cooler unit internal temperature to be adjusted; an AC power supply adapted to receive AC power when available; a DC power jack adapted to receive DC power when available; a rechargeable battery coupled to the AC power supply and to the DC power jack, the rechargeable battery adapted to operate the compressor and the fan when the cooler unit is ON, and the cooler unit is not receiving external power; and a foldable solar panel at least including a photovoltaic array, the solar panel adapted to be functionally stored when folded into the top of the cooler unit, and conduct electricity when exposed to sunlight, and the solar panel adapted to connect via a power cord to the DC power jack and power the cooler unit.
Notwithstanding the above, it is presently believed that there is a need and a potential commercial market for an improved portable ice chest for medical supplies, food supplies and beverages in accordance with the present invention. There should be a demand for the improved ice chest because they are durable, reliable and relatively inexpensive and at the same time can store materials for relatively long periods of time without access to a source of electricity. Further, the devices are relatively easy to clean and treat with sanitizers to thereby provide a relatively sterile environment.